(1) Field of the Invention
The present invention relates to a biometrics authentication technique and more particularly to a finger vein image inputting device used for a finger vein authentication apparatus.
(2) Description of the Related Art
Conventionally, passwords, keys, and seals have been used for personal identification. There is an increasing demand for improving a technique of personal identification as advancement of information society. Attention is focused on the biometrics using bodily characteristics specific to individuals. The biometrics has advantages of excellent convenience and improved security against theft, loss, invalid transfer, or oblivion for the secret data such as credit cards, etc.
The biometrics uses bodily characteristics such as fingerprint, palm, face, iris, voice pattern, and vein for personal authentication. Using finger veins, the finger vein authentication particularly causes less psychological resistance than fingerprints and is hardly falsified.
The finger vein authentication uses the fact that a hemoglobin in blood absorbs near infrared ray having a wavelength range of 700 to 1200 nm. The finger vein authentication applies the near infrared ray to a finger, images a vein pattern inside the finger, and collates the pattern with registered information for personal authentication.
The finger vein authentication provides a higher authentication accuracy than the finger print authentication and is used for cash dispenser or other products that require a high level of security.
Recently, mobile telephones equipped with an electronic money function are widely used. As a countermeasure against loss or theft of the mobile telephones, there is a demand for providing these mobile telephones with a function of authenticating an owner. Actually, some mobile telephones are equipped with finger print authentication devices. For an increased level of security, there is a demand for providing a mobile telephone with a finger vein authentication apparatus. However, the finger vein authentication apparatus needs to be miniaturized so as to be mounted on the mobile telephone.
JP-A No. 28872/2006 discloses an embodiment of using the gradient index lens array and the linear solid-state image sensor for miniaturizing the finger vein authentication apparatus.
The technique in JP-A No. 28872/2006 miniaturizes the finger vein authentication apparatus by using an optical system that applies light to the pad and the side of a finger. The light diffuses in the finger and is transmitted through the finger. The light is imaged under the finger pad to generate a vein image. Since the optical system makes a light source to be close to the finger surface, the light easily reflects on the finger surface, causing an unclear finger vein image due to the reflected light. When a mobile telephone is equipped with the optical system, it is necessary to consider the influence of outside light such as the sunlight because the mobile telephone may be used outdoors or in a bright room.
According to JP-A No. 28872/2006, the light is applied to the finger pad from a light emitting diode (LED) as a light source. JP-A No. 28872/2006 describes no means for decreasing the reflected light on the finger surface. In addition, JP-A No. 28872/2006 describes no means for decreasing the influence of outside light such as the sunlight.
It is therefore an object of the present invention to miniaturize and thin a finger vein authentication apparatus. It is another object of the present invention to provide a finger vein image inputting device capable of high authentication accuracy.